Which invertebrate animals possess a calcium carbonate skeleton?

How many of the following characteristics are common to both Amphibians and Reptiles?
$a$ - Type of fertilization
$b$ - Cold-blooded (Poikilothermic)
$c$ - Development
$d$ - Oviparous
$e$ - Coelomate
$f$ - Bilateral symmetry

Identify the categories $P$,$Q$,and $R$ in the given classification chart of Vertebrata.

Which pair of animal groups contains the respiratory pigment $Hemocyanin$?

Which of the following statements is correct for the given animal group?

Match the organisms given in column-$I$ with their common name given in column-$II$ and choose the correct option.

Column-$I$ (Organisms)	Column-$II$ (Common name)
$A$. Pennatula	$i$. Sea-fan
$B$. Gorgonia	$ii$. Sea-pen
$C$. Adamsia	$iii$. Sea-Anemone
$D$. Cucumaria	$iv$. Sea-cucumber